<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>

    <script>
        let arr = [1,2,3,4,5];
        let arr2 = arr.reduce((a,b) => a+b);
        console.log(arr2)

        let result = arr.reduce((a,b) => a*b);
        console.log(result)

        let result2 = arr.reduce((a,b) => a + b,100);
        console.log(result2)
    </script>
</head>
<body>



</body>
</html>